It tightly couples the record to the platter and the ring provides a flywheel effect that improves speed stability.
There are both very good things for vinyl playback. Worth it? Depends on your priorities and budget. Also, most records are warped to some degree even if you can't see it.
There are both very good things for vinyl playback. Worth it? Depends on your priorities and budget. Also, most records are warped to some degree even if you can't see it.